phoenix-custom-event-hook

This package is a Phoenix LiveView hook that allows you to easily send Custom Events to your live view.

Installation

In your phoenix project assets directory

npm install phoenix-custom-event-hook

Usage

1. Add the PhoenixCustomEvent hook to your LiveSocket

import PhoenixCustomEvent from 'phoenix-custom-event-hook';

let csrfToken = document.querySelector("meta[name='csrf-token']").getAttribute("content")
let liveSocket = new LiveSocket("/live", Socket, { params: { _csrf_token: csrfToken }, hooks: { PhoenixCustomEvent } })

2. Add phx-hook and phx-send-events attributes to elements in your template.

In this example, the lit-google-element emits a bounds_changed custom event which will become live_view event. The payload will be the detail of the custom event, merged with any data- attribute values (the event target dataset). This can be customized if needed (see below).

<lit-google-map api-key="" phx-hook="PhoenixCustomEvent" phx-send-events="bounds_changed">

3. Handle the event in your live view

  def handle_event(
        "bounds_changed",
        %{"north" => north, "east" => east, "west" => west, "south" => south},
        socket
      ) do
    airports =
      Airports.list_airports_in_bounds(%{north: north, east: east, west: west, south: south})

    {:noreply, socket |> assign(airports: airports)}
  end

An target component can be specified by assigning a component id to your custom element's phx-target attribute. In this example, any events emitted by the lit-google-map element will be handled by the LiveComponent that renders it, rather than the LiveView.

<lit-google-map api-key="" phx-hook="PhoenixCustomEvent" phx-target="<%= @myself %>" phx-custom-event-bounds_changed="bounds_changed">

Not currently supported: multiple event targets, targeting events by CSS selector.

Loading events

This hook will also dispatch the following events on the element it is added to:

• phx-event-start when an event is sent to live view
• phx-event-complete when a reply is received

Receiving events

If you wish to receive events from LiveView, add a phx-receive-events attribute to the element this hook is defined on which contains a list of events you wish to receive. Each event will become a CustomEvent of the same name with the detail property containing the payload.

For example, in LiveView:

  socket
  |> push_event("message_updated", %{message: "HI there"})

In your Custom Element:

  this.addEventListener("message_updated", ({ detail: { message } }) => {
    console.log(message);
  });

Event serialization

As of version 0.0.6, the payload for the event pushed to live view will contain:

• the detail property of the custom event
• the dataset from the event target

This will be merged together into the payload sent to LiveView. If you wish to override this behaviour, you may define your own implemention of the serializeEvent function on the hook object, for example:

import PhoenixCustomEvent from 'phoenix-custom-event-hook';
PhoenixCustomEvent.serializeEvent = (_event) => { return {foo: 'bar' } };

License

MIT.